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E. F. Moreira, W. Lee, M. Kantorow, I. R. Rodriguez; Cellular Localization of Peroxiredoxin III in the Primate Retina and Acute Induction in Human RPE Cells. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5046.
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Peroxiredoxins are a diverse family of multifunctional peroxidases with specific cellular distributions. Since loss of mitochondrial function is a key component in the progression of age-related diseases, such as age-related macular degeneration, we investigated the expression of the mitochondrial enzyme, peroxiredoxin III (PrxIII), in the mammalian retina.
Fresh monkey eyes were fixed for 8 hours while a human eye (85 year-old male) was fixed for 17 days in formaldehyde. Eye cups were dissected, embedded and sectioned using a vibrotome at 100-150 µm. Sections were processed for immunocytochemistry using an anti-PrxIII antibody (Abcam Inc.). Image acquisition was done using a Leica SP2 confocal microscope. The primary antibody specificity was confirmed by immunoblot analysis. Induction of PrxIII in response to specific oxidants was examined in RPE19 cells by quantitative RT-PCR and immunoblot analyses.
Immunoblots detected a band of approximately 27 kDa in the neural retina and a slightly smaller weaker band in the RPE/CH. Anti-PrxIII immunostaining detected abundant expression in photoreceptor inner segments (IS) and in cells occupying the ganglion cell layer. Synaptic mitochondria in the outer plexiform layer were weakly labeled. Interestingly, only some cone inner segments were strongly positive for PrxIII. Double labeling studies using anti-opsin antibodies determined these to be blue cones. The human retina displayed an overall similar expression pattern as the monkey, except that all cone inner segments showed similar expression levels. PrxIII was also shown to be induced at least 5-fold above endogenous levels by tertiary-butyl hydroperoxide treatment of cultured human RPE cells.
These results demonstrate that PrxIII is an inducible enzyme expressed mainly in the photoreceptor inner segments mitochondria. These data also suggest that PrxIII may play an important role in protecting photoreceptors from oxidative damage.
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